X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=blobdiff_plain;f=kernel%2Fworkqueue.c;h=bce1074bdec1e826071a38662e43c4d8d74c10bc;hp=327d2deb44515b438c8e43cec56415d85b22342d;hb=18aa9effad4adb2c1efe123af4eb24fec9f59b30;hpb=b904d7131d116900524bd36ec170dcd97846bfd3 diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 327d2deb4451..bce1074bdec1 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -33,41 +33,145 @@ #include #include #include -#define CREATE_TRACE_POINTS -#include +#include + +enum { + /* global_cwq flags */ + GCWQ_FREEZING = 1 << 3, /* freeze in progress */ + + /* worker flags */ + WORKER_STARTED = 1 << 0, /* started */ + WORKER_DIE = 1 << 1, /* die die die */ + WORKER_IDLE = 1 << 2, /* is idle */ + WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ + + /* gcwq->trustee_state */ + TRUSTEE_START = 0, /* start */ + TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ + TRUSTEE_BUTCHER = 2, /* butcher workers */ + TRUSTEE_RELEASE = 3, /* release workers */ + TRUSTEE_DONE = 4, /* trustee is done */ + + BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ + BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, + BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, + + TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ +}; /* - * The per-CPU workqueue (if single thread, we always use the first - * possible cpu). + * Structure fields follow one of the following exclusion rules. + * + * I: Set during initialization and read-only afterwards. + * + * L: gcwq->lock protected. Access with gcwq->lock held. + * + * F: wq->flush_mutex protected. + * + * W: workqueue_lock protected. */ -struct cpu_workqueue_struct { - spinlock_t lock; +struct global_cwq; +struct cpu_workqueue_struct; +struct worker { + /* on idle list while idle, on busy hash table while busy */ + union { + struct list_head entry; /* L: while idle */ + struct hlist_node hentry; /* L: while busy */ + }; + + struct work_struct *current_work; /* L: work being processed */ + struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ + struct list_head scheduled; /* L: scheduled works */ + struct task_struct *task; /* I: worker task */ + struct global_cwq *gcwq; /* I: the associated gcwq */ + struct cpu_workqueue_struct *cwq; /* I: the associated cwq */ + unsigned int flags; /* L: flags */ + int id; /* I: worker id */ +}; + +/* + * Global per-cpu workqueue. + */ +struct global_cwq { + spinlock_t lock; /* the gcwq lock */ + unsigned int cpu; /* I: the associated cpu */ + unsigned int flags; /* L: GCWQ_* flags */ + + int nr_workers; /* L: total number of workers */ + int nr_idle; /* L: currently idle ones */ + + /* workers are chained either in the idle_list or busy_hash */ + struct list_head idle_list; /* L: list of idle workers */ + struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; + /* L: hash of busy workers */ + + struct ida worker_ida; /* L: for worker IDs */ + + struct task_struct *trustee; /* L: for gcwq shutdown */ + unsigned int trustee_state; /* L: trustee state */ + wait_queue_head_t trustee_wait; /* trustee wait */ +} ____cacheline_aligned_in_smp; + +/* + * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of + * work_struct->data are used for flags and thus cwqs need to be + * aligned at two's power of the number of flag bits. + */ +struct cpu_workqueue_struct { + struct global_cwq *gcwq; /* I: the associated gcwq */ struct list_head worklist; - wait_queue_head_t more_work; - struct work_struct *current_work; + struct worker *worker; + struct workqueue_struct *wq; /* I: the owning workqueue */ + int work_color; /* L: current color */ + int flush_color; /* L: flushing color */ + int nr_in_flight[WORK_NR_COLORS]; + /* L: nr of in_flight works */ + int nr_active; /* L: nr of active works */ + int max_active; /* L: max active works */ + struct list_head delayed_works; /* L: delayed works */ +}; - struct workqueue_struct *wq; - struct task_struct *thread; -} ____cacheline_aligned; +/* + * Structure used to wait for workqueue flush. + */ +struct wq_flusher { + struct list_head list; /* F: list of flushers */ + int flush_color; /* F: flush color waiting for */ + struct completion done; /* flush completion */ +}; /* * The externally visible workqueue abstraction is an array of * per-CPU workqueues: */ struct workqueue_struct { - struct cpu_workqueue_struct *cpu_wq; - struct list_head list; - const char *name; - int singlethread; - int freezeable; /* Freeze threads during suspend */ - int rt; + unsigned int flags; /* I: WQ_* flags */ + struct cpu_workqueue_struct *cpu_wq; /* I: cwq's */ + struct list_head list; /* W: list of all workqueues */ + + struct mutex flush_mutex; /* protects wq flushing */ + int work_color; /* F: current work color */ + int flush_color; /* F: current flush color */ + atomic_t nr_cwqs_to_flush; /* flush in progress */ + struct wq_flusher *first_flusher; /* F: first flusher */ + struct list_head flusher_queue; /* F: flush waiters */ + struct list_head flusher_overflow; /* F: flush overflow list */ + + unsigned long single_cpu; /* cpu for single cpu wq */ + + int saved_max_active; /* I: saved cwq max_active */ + const char *name; /* I: workqueue name */ #ifdef CONFIG_LOCKDEP - struct lockdep_map lockdep_map; + struct lockdep_map lockdep_map; #endif }; +#define for_each_busy_worker(worker, i, pos, gcwq) \ + for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ + hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) + #ifdef CONFIG_DEBUG_OBJECTS_WORK static struct debug_obj_descr work_debug_descr; @@ -107,7 +211,7 @@ static int work_fixup_activate(void *addr, enum debug_obj_state state) * statically initialized. We just make sure that it * is tracked in the object tracker. */ - if (test_bit(WORK_STRUCT_STATIC, work_data_bits(work))) { + if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { debug_object_init(work, &work_debug_descr); debug_object_activate(work, &work_debug_descr); return 0; @@ -181,94 +285,336 @@ static inline void debug_work_deactivate(struct work_struct *work) { } /* Serializes the accesses to the list of workqueues. */ static DEFINE_SPINLOCK(workqueue_lock); static LIST_HEAD(workqueues); +static bool workqueue_freezing; /* W: have wqs started freezing? */ + +static DEFINE_PER_CPU(struct global_cwq, global_cwq); + +static int worker_thread(void *__worker); + +static struct global_cwq *get_gcwq(unsigned int cpu) +{ + return &per_cpu(global_cwq, cpu); +} + +static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, + struct workqueue_struct *wq) +{ + return per_cpu_ptr(wq->cpu_wq, cpu); +} + +static unsigned int work_color_to_flags(int color) +{ + return color << WORK_STRUCT_COLOR_SHIFT; +} + +static int get_work_color(struct work_struct *work) +{ + return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & + ((1 << WORK_STRUCT_COLOR_BITS) - 1); +} + +static int work_next_color(int color) +{ + return (color + 1) % WORK_NR_COLORS; +} -static int singlethread_cpu __read_mostly; -static const struct cpumask *cpu_singlethread_map __read_mostly; /* - * _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD - * flushes cwq->worklist. This means that flush_workqueue/wait_on_work - * which comes in between can't use for_each_online_cpu(). We could - * use cpu_possible_map, the cpumask below is more a documentation - * than optimization. + * Work data points to the cwq while a work is on queue. Once + * execution starts, it points to the cpu the work was last on. This + * can be distinguished by comparing the data value against + * PAGE_OFFSET. + * + * set_work_{cwq|cpu}() and clear_work_data() can be used to set the + * cwq, cpu or clear work->data. These functions should only be + * called while the work is owned - ie. while the PENDING bit is set. + * + * get_work_[g]cwq() can be used to obtain the gcwq or cwq + * corresponding to a work. gcwq is available once the work has been + * queued anywhere after initialization. cwq is available only from + * queueing until execution starts. */ -static cpumask_var_t cpu_populated_map __read_mostly; +static inline void set_work_data(struct work_struct *work, unsigned long data, + unsigned long flags) +{ + BUG_ON(!work_pending(work)); + atomic_long_set(&work->data, data | flags | work_static(work)); +} -/* If it's single threaded, it isn't in the list of workqueues. */ -static inline int is_wq_single_threaded(struct workqueue_struct *wq) +static void set_work_cwq(struct work_struct *work, + struct cpu_workqueue_struct *cwq, + unsigned long extra_flags) { - return wq->singlethread; + set_work_data(work, (unsigned long)cwq, + WORK_STRUCT_PENDING | extra_flags); } -static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq) +static void set_work_cpu(struct work_struct *work, unsigned int cpu) { - return is_wq_single_threaded(wq) - ? cpu_singlethread_map : cpu_populated_map; + set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); } -static -struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu) +static void clear_work_data(struct work_struct *work) { - if (unlikely(is_wq_single_threaded(wq))) - cpu = singlethread_cpu; - return per_cpu_ptr(wq->cpu_wq, cpu); + set_work_data(work, WORK_STRUCT_NO_CPU, 0); } -/* - * Set the workqueue on which a work item is to be run - * - Must *only* be called if the pending flag is set +static inline unsigned long get_work_data(struct work_struct *work) +{ + return atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK; +} + +static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) +{ + unsigned long data = get_work_data(work); + + return data >= PAGE_OFFSET ? (void *)data : NULL; +} + +static struct global_cwq *get_work_gcwq(struct work_struct *work) +{ + unsigned long data = get_work_data(work); + unsigned int cpu; + + if (data >= PAGE_OFFSET) + return ((struct cpu_workqueue_struct *)data)->gcwq; + + cpu = data >> WORK_STRUCT_FLAG_BITS; + if (cpu == NR_CPUS) + return NULL; + + BUG_ON(cpu >= num_possible_cpus()); + return get_gcwq(cpu); +} + +/** + * busy_worker_head - return the busy hash head for a work + * @gcwq: gcwq of interest + * @work: work to be hashed + * + * Return hash head of @gcwq for @work. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + * + * RETURNS: + * Pointer to the hash head. */ -static inline void set_wq_data(struct work_struct *work, - struct cpu_workqueue_struct *cwq) +static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, + struct work_struct *work) { - unsigned long new; + const int base_shift = ilog2(sizeof(struct work_struct)); + unsigned long v = (unsigned long)work; - BUG_ON(!work_pending(work)); + /* simple shift and fold hash, do we need something better? */ + v >>= base_shift; + v += v >> BUSY_WORKER_HASH_ORDER; + v &= BUSY_WORKER_HASH_MASK; - new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING); - new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work); - atomic_long_set(&work->data, new); + return &gcwq->busy_hash[v]; } -/* - * Clear WORK_STRUCT_PENDING and the workqueue on which it was queued. +/** + * __find_worker_executing_work - find worker which is executing a work + * @gcwq: gcwq of interest + * @bwh: hash head as returned by busy_worker_head() + * @work: work to find worker for + * + * Find a worker which is executing @work on @gcwq. @bwh should be + * the hash head obtained by calling busy_worker_head() with the same + * work. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + * + * RETURNS: + * Pointer to worker which is executing @work if found, NULL + * otherwise. */ -static inline void clear_wq_data(struct work_struct *work) +static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, + struct hlist_head *bwh, + struct work_struct *work) { - unsigned long flags = *work_data_bits(work) & - (1UL << WORK_STRUCT_STATIC); - atomic_long_set(&work->data, flags); + struct worker *worker; + struct hlist_node *tmp; + + hlist_for_each_entry(worker, tmp, bwh, hentry) + if (worker->current_work == work) + return worker; + return NULL; } -static inline -struct cpu_workqueue_struct *get_wq_data(struct work_struct *work) +/** + * find_worker_executing_work - find worker which is executing a work + * @gcwq: gcwq of interest + * @work: work to find worker for + * + * Find a worker which is executing @work on @gcwq. This function is + * identical to __find_worker_executing_work() except that this + * function calculates @bwh itself. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + * + * RETURNS: + * Pointer to worker which is executing @work if found, NULL + * otherwise. + */ +static struct worker *find_worker_executing_work(struct global_cwq *gcwq, + struct work_struct *work) { - return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK); + return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), + work); } +/** + * insert_work - insert a work into cwq + * @cwq: cwq @work belongs to + * @work: work to insert + * @head: insertion point + * @extra_flags: extra WORK_STRUCT_* flags to set + * + * Insert @work into @cwq after @head. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + */ static void insert_work(struct cpu_workqueue_struct *cwq, - struct work_struct *work, struct list_head *head) + struct work_struct *work, struct list_head *head, + unsigned int extra_flags) { - trace_workqueue_insertion(cwq->thread, work); + /* we own @work, set data and link */ + set_work_cwq(work, cwq, extra_flags); - set_wq_data(work, cwq); /* * Ensure that we get the right work->data if we see the * result of list_add() below, see try_to_grab_pending(). */ smp_wmb(); + list_add_tail(&work->entry, head); - wake_up(&cwq->more_work); + wake_up_process(cwq->worker->task); +} + +/** + * cwq_unbind_single_cpu - unbind cwq from single cpu workqueue processing + * @cwq: cwq to unbind + * + * Try to unbind @cwq from single cpu workqueue processing. If + * @cwq->wq is frozen, unbind is delayed till the workqueue is thawed. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + */ +static void cwq_unbind_single_cpu(struct cpu_workqueue_struct *cwq) +{ + struct workqueue_struct *wq = cwq->wq; + struct global_cwq *gcwq = cwq->gcwq; + + BUG_ON(wq->single_cpu != gcwq->cpu); + /* + * Unbind from workqueue if @cwq is not frozen. If frozen, + * thaw_workqueues() will either restart processing on this + * cpu or unbind if empty. This keeps works queued while + * frozen fully ordered and flushable. + */ + if (likely(!(gcwq->flags & GCWQ_FREEZING))) { + smp_wmb(); /* paired with cmpxchg() in __queue_work() */ + wq->single_cpu = NR_CPUS; + } } -static void __queue_work(struct cpu_workqueue_struct *cwq, +static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, struct work_struct *work) { + struct global_cwq *gcwq; + struct cpu_workqueue_struct *cwq; + struct list_head *worklist; unsigned long flags; + bool arbitrate; debug_work_activate(work); - spin_lock_irqsave(&cwq->lock, flags); - insert_work(cwq, work, &cwq->worklist); - spin_unlock_irqrestore(&cwq->lock, flags); + + /* + * Determine gcwq to use. SINGLE_CPU is inherently + * NON_REENTRANT, so test it first. + */ + if (!(wq->flags & WQ_SINGLE_CPU)) { + struct global_cwq *last_gcwq; + + /* + * It's multi cpu. If @wq is non-reentrant and @work + * was previously on a different cpu, it might still + * be running there, in which case the work needs to + * be queued on that cpu to guarantee non-reentrance. + */ + gcwq = get_gcwq(cpu); + if (wq->flags & WQ_NON_REENTRANT && + (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { + struct worker *worker; + + spin_lock_irqsave(&last_gcwq->lock, flags); + + worker = find_worker_executing_work(last_gcwq, work); + + if (worker && worker->current_cwq->wq == wq) + gcwq = last_gcwq; + else { + /* meh... not running there, queue here */ + spin_unlock_irqrestore(&last_gcwq->lock, flags); + spin_lock_irqsave(&gcwq->lock, flags); + } + } else + spin_lock_irqsave(&gcwq->lock, flags); + } else { + unsigned int req_cpu = cpu; + + /* + * It's a bit more complex for single cpu workqueues. + * We first need to determine which cpu is going to be + * used. If no cpu is currently serving this + * workqueue, arbitrate using atomic accesses to + * wq->single_cpu; otherwise, use the current one. + */ + retry: + cpu = wq->single_cpu; + arbitrate = cpu == NR_CPUS; + if (arbitrate) + cpu = req_cpu; + + gcwq = get_gcwq(cpu); + spin_lock_irqsave(&gcwq->lock, flags); + + /* + * The following cmpxchg() is a full barrier paired + * with smp_wmb() in cwq_unbind_single_cpu() and + * guarantees that all changes to wq->st_* fields are + * visible on the new cpu after this point. + */ + if (arbitrate) + cmpxchg(&wq->single_cpu, NR_CPUS, cpu); + + if (unlikely(wq->single_cpu != cpu)) { + spin_unlock_irqrestore(&gcwq->lock, flags); + goto retry; + } + } + + /* gcwq determined, get cwq and queue */ + cwq = get_cwq(gcwq->cpu, wq); + + BUG_ON(!list_empty(&work->entry)); + + cwq->nr_in_flight[cwq->work_color]++; + + if (likely(cwq->nr_active < cwq->max_active)) { + cwq->nr_active++; + worklist = &cwq->worklist; + } else + worklist = &cwq->delayed_works; + + insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color)); + + spin_unlock_irqrestore(&gcwq->lock, flags); } /** @@ -308,9 +654,8 @@ queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) { int ret = 0; - if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { - BUG_ON(!list_empty(&work->entry)); - __queue_work(wq_per_cpu(wq, cpu), work); + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { + __queue_work(cpu, wq, work); ret = 1; } return ret; @@ -320,10 +665,9 @@ EXPORT_SYMBOL_GPL(queue_work_on); static void delayed_work_timer_fn(unsigned long __data) { struct delayed_work *dwork = (struct delayed_work *)__data; - struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work); - struct workqueue_struct *wq = cwq->wq; + struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); - __queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work); + __queue_work(smp_processor_id(), cwq->wq, &dwork->work); } /** @@ -360,14 +704,20 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, struct timer_list *timer = &dwork->timer; struct work_struct *work = &dwork->work; - if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { + struct global_cwq *gcwq = get_work_gcwq(work); + unsigned int lcpu = gcwq ? gcwq->cpu : raw_smp_processor_id(); + BUG_ON(timer_pending(timer)); BUG_ON(!list_empty(&work->entry)); timer_stats_timer_set_start_info(&dwork->timer); - - /* This stores cwq for the moment, for the timer_fn */ - set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id())); + /* + * This stores cwq for the moment, for the timer_fn. + * Note that the work's gcwq is preserved to allow + * reentrance detection for delayed works. + */ + set_work_cwq(work, get_cwq(lcpu, wq), 0); timer->expires = jiffies + delay; timer->data = (unsigned long)dwork; timer->function = delayed_work_timer_fn; @@ -382,80 +732,444 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, } EXPORT_SYMBOL_GPL(queue_delayed_work_on); -static void run_workqueue(struct cpu_workqueue_struct *cwq) +/** + * worker_enter_idle - enter idle state + * @worker: worker which is entering idle state + * + * @worker is entering idle state. Update stats and idle timer if + * necessary. + * + * LOCKING: + * spin_lock_irq(gcwq->lock). + */ +static void worker_enter_idle(struct worker *worker) { - spin_lock_irq(&cwq->lock); - while (!list_empty(&cwq->worklist)) { - struct work_struct *work = list_entry(cwq->worklist.next, - struct work_struct, entry); - work_func_t f = work->func; + struct global_cwq *gcwq = worker->gcwq; + + BUG_ON(worker->flags & WORKER_IDLE); + BUG_ON(!list_empty(&worker->entry) && + (worker->hentry.next || worker->hentry.pprev)); + + worker->flags |= WORKER_IDLE; + gcwq->nr_idle++; + + /* idle_list is LIFO */ + list_add(&worker->entry, &gcwq->idle_list); + + if (unlikely(worker->flags & WORKER_ROGUE)) + wake_up_all(&gcwq->trustee_wait); +} + +/** + * worker_leave_idle - leave idle state + * @worker: worker which is leaving idle state + * + * @worker is leaving idle state. Update stats. + * + * LOCKING: + * spin_lock_irq(gcwq->lock). + */ +static void worker_leave_idle(struct worker *worker) +{ + struct global_cwq *gcwq = worker->gcwq; + + BUG_ON(!(worker->flags & WORKER_IDLE)); + worker->flags &= ~WORKER_IDLE; + gcwq->nr_idle--; + list_del_init(&worker->entry); +} + +static struct worker *alloc_worker(void) +{ + struct worker *worker; + + worker = kzalloc(sizeof(*worker), GFP_KERNEL); + if (worker) { + INIT_LIST_HEAD(&worker->entry); + INIT_LIST_HEAD(&worker->scheduled); + } + return worker; +} + +/** + * create_worker - create a new workqueue worker + * @cwq: cwq the new worker will belong to + * @bind: whether to set affinity to @cpu or not + * + * Create a new worker which is bound to @cwq. The returned worker + * can be started by calling start_worker() or destroyed using + * destroy_worker(). + * + * CONTEXT: + * Might sleep. Does GFP_KERNEL allocations. + * + * RETURNS: + * Pointer to the newly created worker. + */ +static struct worker *create_worker(struct cpu_workqueue_struct *cwq, bool bind) +{ + struct global_cwq *gcwq = cwq->gcwq; + int id = -1; + struct worker *worker = NULL; + + spin_lock_irq(&gcwq->lock); + while (ida_get_new(&gcwq->worker_ida, &id)) { + spin_unlock_irq(&gcwq->lock); + if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) + goto fail; + spin_lock_irq(&gcwq->lock); + } + spin_unlock_irq(&gcwq->lock); + + worker = alloc_worker(); + if (!worker) + goto fail; + + worker->gcwq = gcwq; + worker->cwq = cwq; + worker->id = id; + + worker->task = kthread_create(worker_thread, worker, "kworker/%u:%d", + gcwq->cpu, id); + if (IS_ERR(worker->task)) + goto fail; + + /* + * A rogue worker will become a regular one if CPU comes + * online later on. Make sure every worker has + * PF_THREAD_BOUND set. + */ + if (bind) + kthread_bind(worker->task, gcwq->cpu); + else + worker->task->flags |= PF_THREAD_BOUND; + + return worker; +fail: + if (id >= 0) { + spin_lock_irq(&gcwq->lock); + ida_remove(&gcwq->worker_ida, id); + spin_unlock_irq(&gcwq->lock); + } + kfree(worker); + return NULL; +} + +/** + * start_worker - start a newly created worker + * @worker: worker to start + * + * Make the gcwq aware of @worker and start it. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + */ +static void start_worker(struct worker *worker) +{ + worker->flags |= WORKER_STARTED; + worker->gcwq->nr_workers++; + worker_enter_idle(worker); + wake_up_process(worker->task); +} + +/** + * destroy_worker - destroy a workqueue worker + * @worker: worker to be destroyed + * + * Destroy @worker and adjust @gcwq stats accordingly. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock) which is released and regrabbed. + */ +static void destroy_worker(struct worker *worker) +{ + struct global_cwq *gcwq = worker->gcwq; + int id = worker->id; + + /* sanity check frenzy */ + BUG_ON(worker->current_work); + BUG_ON(!list_empty(&worker->scheduled)); + + if (worker->flags & WORKER_STARTED) + gcwq->nr_workers--; + if (worker->flags & WORKER_IDLE) + gcwq->nr_idle--; + + list_del_init(&worker->entry); + worker->flags |= WORKER_DIE; + + spin_unlock_irq(&gcwq->lock); + + kthread_stop(worker->task); + kfree(worker); + + spin_lock_irq(&gcwq->lock); + ida_remove(&gcwq->worker_ida, id); +} + +/** + * move_linked_works - move linked works to a list + * @work: start of series of works to be scheduled + * @head: target list to append @work to + * @nextp: out paramter for nested worklist walking + * + * Schedule linked works starting from @work to @head. Work series to + * be scheduled starts at @work and includes any consecutive work with + * WORK_STRUCT_LINKED set in its predecessor. + * + * If @nextp is not NULL, it's updated to point to the next work of + * the last scheduled work. This allows move_linked_works() to be + * nested inside outer list_for_each_entry_safe(). + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + */ +static void move_linked_works(struct work_struct *work, struct list_head *head, + struct work_struct **nextp) +{ + struct work_struct *n; + + /* + * Linked worklist will always end before the end of the list, + * use NULL for list head. + */ + list_for_each_entry_safe_from(work, n, NULL, entry) { + list_move_tail(&work->entry, head); + if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) + break; + } + + /* + * If we're already inside safe list traversal and have moved + * multiple works to the scheduled queue, the next position + * needs to be updated. + */ + if (nextp) + *nextp = n; +} + +static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) +{ + struct work_struct *work = list_first_entry(&cwq->delayed_works, + struct work_struct, entry); + + move_linked_works(work, &cwq->worklist, NULL); + cwq->nr_active++; +} + +/** + * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight + * @cwq: cwq of interest + * @color: color of work which left the queue + * + * A work either has completed or is removed from pending queue, + * decrement nr_in_flight of its cwq and handle workqueue flushing. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + */ +static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color) +{ + /* ignore uncolored works */ + if (color == WORK_NO_COLOR) + return; + + cwq->nr_in_flight[color]--; + cwq->nr_active--; + + if (!list_empty(&cwq->delayed_works)) { + /* one down, submit a delayed one */ + if (cwq->nr_active < cwq->max_active) + cwq_activate_first_delayed(cwq); + } else if (!cwq->nr_active && cwq->wq->flags & WQ_SINGLE_CPU) { + /* this was the last work, unbind from single cpu */ + cwq_unbind_single_cpu(cwq); + } + + /* is flush in progress and are we at the flushing tip? */ + if (likely(cwq->flush_color != color)) + return; + + /* are there still in-flight works? */ + if (cwq->nr_in_flight[color]) + return; + + /* this cwq is done, clear flush_color */ + cwq->flush_color = -1; + + /* + * If this was the last cwq, wake up the first flusher. It + * will handle the rest. + */ + if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) + complete(&cwq->wq->first_flusher->done); +} + +/** + * process_one_work - process single work + * @worker: self + * @work: work to process + * + * Process @work. This function contains all the logics necessary to + * process a single work including synchronization against and + * interaction with other workers on the same cpu, queueing and + * flushing. As long as context requirement is met, any worker can + * call this function to process a work. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock) which is released and regrabbed. + */ +static void process_one_work(struct worker *worker, struct work_struct *work) +{ + struct cpu_workqueue_struct *cwq = worker->cwq; + struct global_cwq *gcwq = cwq->gcwq; + struct hlist_head *bwh = busy_worker_head(gcwq, work); + work_func_t f = work->func; + int work_color; #ifdef CONFIG_LOCKDEP - /* - * It is permissible to free the struct work_struct - * from inside the function that is called from it, - * this we need to take into account for lockdep too. - * To avoid bogus "held lock freed" warnings as well - * as problems when looking into work->lockdep_map, - * make a copy and use that here. - */ - struct lockdep_map lockdep_map = work->lockdep_map; + /* + * It is permissible to free the struct work_struct from + * inside the function that is called from it, this we need to + * take into account for lockdep too. To avoid bogus "held + * lock freed" warnings as well as problems when looking into + * work->lockdep_map, make a copy and use that here. + */ + struct lockdep_map lockdep_map = work->lockdep_map; #endif - trace_workqueue_execution(cwq->thread, work); - debug_work_deactivate(work); - cwq->current_work = work; - list_del_init(cwq->worklist.next); - spin_unlock_irq(&cwq->lock); - - BUG_ON(get_wq_data(work) != cwq); - work_clear_pending(work); - lock_map_acquire(&cwq->wq->lockdep_map); - lock_map_acquire(&lockdep_map); - f(work); - lock_map_release(&lockdep_map); - lock_map_release(&cwq->wq->lockdep_map); - - if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { - printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " - "%s/0x%08x/%d\n", - current->comm, preempt_count(), - task_pid_nr(current)); - printk(KERN_ERR " last function: "); - print_symbol("%s\n", (unsigned long)f); - debug_show_held_locks(current); - dump_stack(); - } + /* claim and process */ + debug_work_deactivate(work); + hlist_add_head(&worker->hentry, bwh); + worker->current_work = work; + worker->current_cwq = cwq; + work_color = get_work_color(work); + + BUG_ON(get_work_cwq(work) != cwq); + /* record the current cpu number in the work data and dequeue */ + set_work_cpu(work, gcwq->cpu); + list_del_init(&work->entry); + + spin_unlock_irq(&gcwq->lock); + + work_clear_pending(work); + lock_map_acquire(&cwq->wq->lockdep_map); + lock_map_acquire(&lockdep_map); + f(work); + lock_map_release(&lockdep_map); + lock_map_release(&cwq->wq->lockdep_map); + + if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { + printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " + "%s/0x%08x/%d\n", + current->comm, preempt_count(), task_pid_nr(current)); + printk(KERN_ERR " last function: "); + print_symbol("%s\n", (unsigned long)f); + debug_show_held_locks(current); + dump_stack(); + } + + spin_lock_irq(&gcwq->lock); + + /* we're done with it, release */ + hlist_del_init(&worker->hentry); + worker->current_work = NULL; + worker->current_cwq = NULL; + cwq_dec_nr_in_flight(cwq, work_color); +} - spin_lock_irq(&cwq->lock); - cwq->current_work = NULL; +/** + * process_scheduled_works - process scheduled works + * @worker: self + * + * Process all scheduled works. Please note that the scheduled list + * may change while processing a work, so this function repeatedly + * fetches a work from the top and executes it. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock) which may be released and regrabbed + * multiple times. + */ +static void process_scheduled_works(struct worker *worker) +{ + while (!list_empty(&worker->scheduled)) { + struct work_struct *work = list_first_entry(&worker->scheduled, + struct work_struct, entry); + process_one_work(worker, work); } - spin_unlock_irq(&cwq->lock); } -static int worker_thread(void *__cwq) +/** + * worker_thread - the worker thread function + * @__worker: self + * + * The cwq worker thread function. + */ +static int worker_thread(void *__worker) { - struct cpu_workqueue_struct *cwq = __cwq; - DEFINE_WAIT(wait); + struct worker *worker = __worker; + struct global_cwq *gcwq = worker->gcwq; + struct cpu_workqueue_struct *cwq = worker->cwq; - if (cwq->wq->freezeable) - set_freezable(); +woke_up: + spin_lock_irq(&gcwq->lock); - for (;;) { - prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE); - if (!freezing(current) && - !kthread_should_stop() && - list_empty(&cwq->worklist)) - schedule(); - finish_wait(&cwq->more_work, &wait); + /* DIE can be set only while we're idle, checking here is enough */ + if (worker->flags & WORKER_DIE) { + spin_unlock_irq(&gcwq->lock); + return 0; + } - try_to_freeze(); + worker_leave_idle(worker); +recheck: + /* + * ->scheduled list can only be filled while a worker is + * preparing to process a work or actually processing it. + * Make sure nobody diddled with it while I was sleeping. + */ + BUG_ON(!list_empty(&worker->scheduled)); - if (kthread_should_stop()) - break; + while (!list_empty(&cwq->worklist)) { + struct work_struct *work = + list_first_entry(&cwq->worklist, + struct work_struct, entry); + + /* + * The following is a rather inefficient way to close + * race window against cpu hotplug operations. Will + * be replaced soon. + */ + if (unlikely(!(worker->flags & WORKER_ROGUE) && + !cpumask_equal(&worker->task->cpus_allowed, + get_cpu_mask(gcwq->cpu)))) { + spin_unlock_irq(&gcwq->lock); + set_cpus_allowed_ptr(worker->task, + get_cpu_mask(gcwq->cpu)); + cpu_relax(); + spin_lock_irq(&gcwq->lock); + goto recheck; + } - run_workqueue(cwq); + if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { + /* optimization path, not strictly necessary */ + process_one_work(worker, work); + if (unlikely(!list_empty(&worker->scheduled))) + process_scheduled_works(worker); + } else { + move_linked_works(work, &worker->scheduled, NULL); + process_scheduled_works(worker); + } } - return 0; + /* + * gcwq->lock is held and there's no work to process, sleep. + * Workers are woken up only while holding gcwq->lock, so + * setting the current state before releasing gcwq->lock is + * enough to prevent losing any event. + */ + worker_enter_idle(worker); + __set_current_state(TASK_INTERRUPTIBLE); + spin_unlock_irq(&gcwq->lock); + schedule(); + goto woke_up; } struct wq_barrier { @@ -469,69 +1183,288 @@ static void wq_barrier_func(struct work_struct *work) complete(&barr->done); } +/** + * insert_wq_barrier - insert a barrier work + * @cwq: cwq to insert barrier into + * @barr: wq_barrier to insert + * @target: target work to attach @barr to + * @worker: worker currently executing @target, NULL if @target is not executing + * + * @barr is linked to @target such that @barr is completed only after + * @target finishes execution. Please note that the ordering + * guarantee is observed only with respect to @target and on the local + * cpu. + * + * Currently, a queued barrier can't be canceled. This is because + * try_to_grab_pending() can't determine whether the work to be + * grabbed is at the head of the queue and thus can't clear LINKED + * flag of the previous work while there must be a valid next work + * after a work with LINKED flag set. + * + * Note that when @worker is non-NULL, @target may be modified + * underneath us, so we can't reliably determine cwq from @target. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock). + */ static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, - struct wq_barrier *barr, struct list_head *head) + struct wq_barrier *barr, + struct work_struct *target, struct worker *worker) { + struct list_head *head; + unsigned int linked = 0; + /* - * debugobject calls are safe here even with cwq->lock locked + * debugobject calls are safe here even with gcwq->lock locked * as we know for sure that this will not trigger any of the * checks and call back into the fixup functions where we * might deadlock. */ INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); - __set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work)); - + __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); init_completion(&barr->done); + /* + * If @target is currently being executed, schedule the + * barrier to the worker; otherwise, put it after @target. + */ + if (worker) + head = worker->scheduled.next; + else { + unsigned long *bits = work_data_bits(target); + + head = target->entry.next; + /* there can already be other linked works, inherit and set */ + linked = *bits & WORK_STRUCT_LINKED; + __set_bit(WORK_STRUCT_LINKED_BIT, bits); + } + debug_work_activate(&barr->work); - insert_work(cwq, &barr->work, head); + insert_work(cwq, &barr->work, head, + work_color_to_flags(WORK_NO_COLOR) | linked); } -static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) +/** + * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing + * @wq: workqueue being flushed + * @flush_color: new flush color, < 0 for no-op + * @work_color: new work color, < 0 for no-op + * + * Prepare cwqs for workqueue flushing. + * + * If @flush_color is non-negative, flush_color on all cwqs should be + * -1. If no cwq has in-flight commands at the specified color, all + * cwq->flush_color's stay at -1 and %false is returned. If any cwq + * has in flight commands, its cwq->flush_color is set to + * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq + * wakeup logic is armed and %true is returned. + * + * The caller should have initialized @wq->first_flusher prior to + * calling this function with non-negative @flush_color. If + * @flush_color is negative, no flush color update is done and %false + * is returned. + * + * If @work_color is non-negative, all cwqs should have the same + * work_color which is previous to @work_color and all will be + * advanced to @work_color. + * + * CONTEXT: + * mutex_lock(wq->flush_mutex). + * + * RETURNS: + * %true if @flush_color >= 0 and there's something to flush. %false + * otherwise. + */ +static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, + int flush_color, int work_color) { - int active = 0; - struct wq_barrier barr; + bool wait = false; + unsigned int cpu; + + if (flush_color >= 0) { + BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); + atomic_set(&wq->nr_cwqs_to_flush, 1); + } + + for_each_possible_cpu(cpu) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + struct global_cwq *gcwq = cwq->gcwq; + + spin_lock_irq(&gcwq->lock); + + if (flush_color >= 0) { + BUG_ON(cwq->flush_color != -1); + + if (cwq->nr_in_flight[flush_color]) { + cwq->flush_color = flush_color; + atomic_inc(&wq->nr_cwqs_to_flush); + wait = true; + } + } + + if (work_color >= 0) { + BUG_ON(work_color != work_next_color(cwq->work_color)); + cwq->work_color = work_color; + } + + spin_unlock_irq(&gcwq->lock); + } + + if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) + complete(&wq->first_flusher->done); + + return wait; +} - WARN_ON(cwq->thread == current); +/** + * flush_workqueue - ensure that any scheduled work has run to completion. + * @wq: workqueue to flush + * + * Forces execution of the workqueue and blocks until its completion. + * This is typically used in driver shutdown handlers. + * + * We sleep until all works which were queued on entry have been handled, + * but we are not livelocked by new incoming ones. + */ +void flush_workqueue(struct workqueue_struct *wq) +{ + struct wq_flusher this_flusher = { + .list = LIST_HEAD_INIT(this_flusher.list), + .flush_color = -1, + .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), + }; + int next_color; + + lock_map_acquire(&wq->lockdep_map); + lock_map_release(&wq->lockdep_map); + + mutex_lock(&wq->flush_mutex); + + /* + * Start-to-wait phase + */ + next_color = work_next_color(wq->work_color); + + if (next_color != wq->flush_color) { + /* + * Color space is not full. The current work_color + * becomes our flush_color and work_color is advanced + * by one. + */ + BUG_ON(!list_empty(&wq->flusher_overflow)); + this_flusher.flush_color = wq->work_color; + wq->work_color = next_color; + + if (!wq->first_flusher) { + /* no flush in progress, become the first flusher */ + BUG_ON(wq->flush_color != this_flusher.flush_color); + + wq->first_flusher = &this_flusher; + + if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, + wq->work_color)) { + /* nothing to flush, done */ + wq->flush_color = next_color; + wq->first_flusher = NULL; + goto out_unlock; + } + } else { + /* wait in queue */ + BUG_ON(wq->flush_color == this_flusher.flush_color); + list_add_tail(&this_flusher.list, &wq->flusher_queue); + flush_workqueue_prep_cwqs(wq, -1, wq->work_color); + } + } else { + /* + * Oops, color space is full, wait on overflow queue. + * The next flush completion will assign us + * flush_color and transfer to flusher_queue. + */ + list_add_tail(&this_flusher.list, &wq->flusher_overflow); + } + + mutex_unlock(&wq->flush_mutex); + + wait_for_completion(&this_flusher.done); + + /* + * Wake-up-and-cascade phase + * + * First flushers are responsible for cascading flushes and + * handling overflow. Non-first flushers can simply return. + */ + if (wq->first_flusher != &this_flusher) + return; + + mutex_lock(&wq->flush_mutex); + + wq->first_flusher = NULL; + + BUG_ON(!list_empty(&this_flusher.list)); + BUG_ON(wq->flush_color != this_flusher.flush_color); + + while (true) { + struct wq_flusher *next, *tmp; + + /* complete all the flushers sharing the current flush color */ + list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { + if (next->flush_color != wq->flush_color) + break; + list_del_init(&next->list); + complete(&next->done); + } + + BUG_ON(!list_empty(&wq->flusher_overflow) && + wq->flush_color != work_next_color(wq->work_color)); + + /* this flush_color is finished, advance by one */ + wq->flush_color = work_next_color(wq->flush_color); + + /* one color has been freed, handle overflow queue */ + if (!list_empty(&wq->flusher_overflow)) { + /* + * Assign the same color to all overflowed + * flushers, advance work_color and append to + * flusher_queue. This is the start-to-wait + * phase for these overflowed flushers. + */ + list_for_each_entry(tmp, &wq->flusher_overflow, list) + tmp->flush_color = wq->work_color; + + wq->work_color = work_next_color(wq->work_color); + + list_splice_tail_init(&wq->flusher_overflow, + &wq->flusher_queue); + flush_workqueue_prep_cwqs(wq, -1, wq->work_color); + } + + if (list_empty(&wq->flusher_queue)) { + BUG_ON(wq->flush_color != wq->work_color); + break; + } - spin_lock_irq(&cwq->lock); - if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) { - insert_wq_barrier(cwq, &barr, &cwq->worklist); - active = 1; - } - spin_unlock_irq(&cwq->lock); + /* + * Need to flush more colors. Make the next flusher + * the new first flusher and arm cwqs. + */ + BUG_ON(wq->flush_color == wq->work_color); + BUG_ON(wq->flush_color != next->flush_color); - if (active) { - wait_for_completion(&barr.done); - destroy_work_on_stack(&barr.work); - } + list_del_init(&next->list); + wq->first_flusher = next; - return active; -} + if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) + break; -/** - * flush_workqueue - ensure that any scheduled work has run to completion. - * @wq: workqueue to flush - * - * Forces execution of the workqueue and blocks until its completion. - * This is typically used in driver shutdown handlers. - * - * We sleep until all works which were queued on entry have been handled, - * but we are not livelocked by new incoming ones. - * - * This function used to run the workqueues itself. Now we just wait for the - * helper threads to do it. - */ -void flush_workqueue(struct workqueue_struct *wq) -{ - const struct cpumask *cpu_map = wq_cpu_map(wq); - int cpu; + /* + * Meh... this color is already done, clear first + * flusher and repeat cascading. + */ + wq->first_flusher = NULL; + } - might_sleep(); - lock_map_acquire(&wq->lockdep_map); - lock_map_release(&wq->lockdep_map); - for_each_cpu(cpu, cpu_map) - flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu)); +out_unlock: + mutex_unlock(&wq->flush_mutex); } EXPORT_SYMBOL_GPL(flush_workqueue); @@ -547,43 +1480,46 @@ EXPORT_SYMBOL_GPL(flush_workqueue); */ int flush_work(struct work_struct *work) { + struct worker *worker = NULL; + struct global_cwq *gcwq; struct cpu_workqueue_struct *cwq; - struct list_head *prev; struct wq_barrier barr; might_sleep(); - cwq = get_wq_data(work); - if (!cwq) + gcwq = get_work_gcwq(work); + if (!gcwq) return 0; - lock_map_acquire(&cwq->wq->lockdep_map); - lock_map_release(&cwq->wq->lockdep_map); - - prev = NULL; - spin_lock_irq(&cwq->lock); + spin_lock_irq(&gcwq->lock); if (!list_empty(&work->entry)) { /* * See the comment near try_to_grab_pending()->smp_rmb(). - * If it was re-queued under us we are not going to wait. + * If it was re-queued to a different gcwq under us, we + * are not going to wait. */ smp_rmb(); - if (unlikely(cwq != get_wq_data(work))) - goto out; - prev = &work->entry; + cwq = get_work_cwq(work); + if (unlikely(!cwq || gcwq != cwq->gcwq)) + goto already_gone; } else { - if (cwq->current_work != work) - goto out; - prev = &cwq->worklist; + worker = find_worker_executing_work(gcwq, work); + if (!worker) + goto already_gone; + cwq = worker->current_cwq; } - insert_wq_barrier(cwq, &barr, prev->next); -out: - spin_unlock_irq(&cwq->lock); - if (!prev) - return 0; + + insert_wq_barrier(cwq, &barr, work, worker); + spin_unlock_irq(&gcwq->lock); + + lock_map_acquire(&cwq->wq->lockdep_map); + lock_map_release(&cwq->wq->lockdep_map); wait_for_completion(&barr.done); destroy_work_on_stack(&barr.work); return 1; +already_gone: + spin_unlock_irq(&gcwq->lock); + return 0; } EXPORT_SYMBOL_GPL(flush_work); @@ -593,54 +1529,55 @@ EXPORT_SYMBOL_GPL(flush_work); */ static int try_to_grab_pending(struct work_struct *work) { - struct cpu_workqueue_struct *cwq; + struct global_cwq *gcwq; int ret = -1; - if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) return 0; /* * The queueing is in progress, or it is already queued. Try to * steal it from ->worklist without clearing WORK_STRUCT_PENDING. */ - - cwq = get_wq_data(work); - if (!cwq) + gcwq = get_work_gcwq(work); + if (!gcwq) return ret; - spin_lock_irq(&cwq->lock); + spin_lock_irq(&gcwq->lock); if (!list_empty(&work->entry)) { /* - * This work is queued, but perhaps we locked the wrong cwq. + * This work is queued, but perhaps we locked the wrong gcwq. * In that case we must see the new value after rmb(), see * insert_work()->wmb(). */ smp_rmb(); - if (cwq == get_wq_data(work)) { + if (gcwq == get_work_gcwq(work)) { debug_work_deactivate(work); list_del_init(&work->entry); + cwq_dec_nr_in_flight(get_work_cwq(work), + get_work_color(work)); ret = 1; } } - spin_unlock_irq(&cwq->lock); + spin_unlock_irq(&gcwq->lock); return ret; } -static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq, - struct work_struct *work) +static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) { struct wq_barrier barr; - int running = 0; + struct worker *worker; - spin_lock_irq(&cwq->lock); - if (unlikely(cwq->current_work == work)) { - insert_wq_barrier(cwq, &barr, cwq->worklist.next); - running = 1; - } - spin_unlock_irq(&cwq->lock); + spin_lock_irq(&gcwq->lock); + + worker = find_worker_executing_work(gcwq, work); + if (unlikely(worker)) + insert_wq_barrier(worker->current_cwq, &barr, work, worker); - if (unlikely(running)) { + spin_unlock_irq(&gcwq->lock); + + if (unlikely(worker)) { wait_for_completion(&barr.done); destroy_work_on_stack(&barr.work); } @@ -648,9 +1585,6 @@ static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq, static void wait_on_work(struct work_struct *work) { - struct cpu_workqueue_struct *cwq; - struct workqueue_struct *wq; - const struct cpumask *cpu_map; int cpu; might_sleep(); @@ -658,15 +1592,8 @@ static void wait_on_work(struct work_struct *work) lock_map_acquire(&work->lockdep_map); lock_map_release(&work->lockdep_map); - cwq = get_wq_data(work); - if (!cwq) - return; - - wq = cwq->wq; - cpu_map = wq_cpu_map(wq); - - for_each_cpu(cpu, cpu_map) - wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work); + for_each_possible_cpu(cpu) + wait_on_cpu_work(get_gcwq(cpu), work); } static int __cancel_work_timer(struct work_struct *work, @@ -681,7 +1608,7 @@ static int __cancel_work_timer(struct work_struct *work, wait_on_work(work); } while (unlikely(ret < 0)); - clear_wq_data(work); + clear_work_data(work); return ret; } @@ -783,9 +1710,8 @@ EXPORT_SYMBOL(schedule_delayed_work); void flush_delayed_work(struct delayed_work *dwork) { if (del_timer_sync(&dwork->timer)) { - struct cpu_workqueue_struct *cwq; - cwq = wq_per_cpu(get_wq_data(&dwork->work)->wq, get_cpu()); - __queue_work(cwq, &dwork->work); + __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq, + &dwork->work); put_cpu(); } flush_work(&dwork->work); @@ -924,160 +1850,152 @@ int current_is_keventd(void) BUG_ON(!keventd_wq); - cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu); - if (current == cwq->thread) + cwq = get_cwq(cpu, keventd_wq); + if (current == cwq->worker->task) ret = 1; return ret; } -static struct cpu_workqueue_struct * -init_cpu_workqueue(struct workqueue_struct *wq, int cpu) +static struct cpu_workqueue_struct *alloc_cwqs(void) { - struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu); - - cwq->wq = wq; - spin_lock_init(&cwq->lock); - INIT_LIST_HEAD(&cwq->worklist); - init_waitqueue_head(&cwq->more_work); - - return cwq; -} - -static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) -{ - struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; - struct workqueue_struct *wq = cwq->wq; - const char *fmt = is_wq_single_threaded(wq) ? "%s" : "%s/%d"; - struct task_struct *p; - - p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu); /* - * Nobody can add the work_struct to this cwq, - * if (caller is __create_workqueue) - * nobody should see this wq - * else // caller is CPU_UP_PREPARE - * cpu is not on cpu_online_map - * so we can abort safely. + * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. + * Make sure that the alignment isn't lower than that of + * unsigned long long. */ - if (IS_ERR(p)) - return PTR_ERR(p); - if (cwq->wq->rt) - sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); - cwq->thread = p; - - trace_workqueue_creation(cwq->thread, cpu); + const size_t size = sizeof(struct cpu_workqueue_struct); + const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, + __alignof__(unsigned long long)); + struct cpu_workqueue_struct *cwqs; +#ifndef CONFIG_SMP + void *ptr; - return 0; + /* + * On UP, percpu allocator doesn't honor alignment parameter + * and simply uses arch-dependent default. Allocate enough + * room to align cwq and put an extra pointer at the end + * pointing back to the originally allocated pointer which + * will be used for free. + * + * FIXME: This really belongs to UP percpu code. Update UP + * percpu code to honor alignment and remove this ugliness. + */ + ptr = __alloc_percpu(size + align + sizeof(void *), 1); + cwqs = PTR_ALIGN(ptr, align); + *(void **)per_cpu_ptr(cwqs + 1, 0) = ptr; +#else + /* On SMP, percpu allocator can do it itself */ + cwqs = __alloc_percpu(size, align); +#endif + /* just in case, make sure it's actually aligned */ + BUG_ON(!IS_ALIGNED((unsigned long)cwqs, align)); + return cwqs; } -static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) +static void free_cwqs(struct cpu_workqueue_struct *cwqs) { - struct task_struct *p = cwq->thread; - - if (p != NULL) { - if (cpu >= 0) - kthread_bind(p, cpu); - wake_up_process(p); - } +#ifndef CONFIG_SMP + /* on UP, the pointer to free is stored right after the cwq */ + if (cwqs) + free_percpu(*(void **)per_cpu_ptr(cwqs + 1, 0)); +#else + free_percpu(cwqs); +#endif } struct workqueue_struct *__create_workqueue_key(const char *name, - int singlethread, - int freezeable, - int rt, + unsigned int flags, + int max_active, struct lock_class_key *key, const char *lock_name) { struct workqueue_struct *wq; - struct cpu_workqueue_struct *cwq; - int err = 0, cpu; + bool failed = false; + unsigned int cpu; + + max_active = clamp_val(max_active, 1, INT_MAX); wq = kzalloc(sizeof(*wq), GFP_KERNEL); if (!wq) - return NULL; + goto err; - wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct); - if (!wq->cpu_wq) { - kfree(wq); - return NULL; - } + wq->cpu_wq = alloc_cwqs(); + if (!wq->cpu_wq) + goto err; + + wq->flags = flags; + wq->saved_max_active = max_active; + mutex_init(&wq->flush_mutex); + atomic_set(&wq->nr_cwqs_to_flush, 0); + INIT_LIST_HEAD(&wq->flusher_queue); + INIT_LIST_HEAD(&wq->flusher_overflow); + wq->single_cpu = NR_CPUS; wq->name = name; lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); - wq->singlethread = singlethread; - wq->freezeable = freezeable; - wq->rt = rt; INIT_LIST_HEAD(&wq->list); - if (singlethread) { - cwq = init_cpu_workqueue(wq, singlethread_cpu); - err = create_workqueue_thread(cwq, singlethread_cpu); - start_workqueue_thread(cwq, -1); - } else { - cpu_maps_update_begin(); - /* - * We must place this wq on list even if the code below fails. - * cpu_down(cpu) can remove cpu from cpu_populated_map before - * destroy_workqueue() takes the lock, in that case we leak - * cwq[cpu]->thread. - */ - spin_lock(&workqueue_lock); - list_add(&wq->list, &workqueues); - spin_unlock(&workqueue_lock); - /* - * We must initialize cwqs for each possible cpu even if we - * are going to call destroy_workqueue() finally. Otherwise - * cpu_up() can hit the uninitialized cwq once we drop the - * lock. - */ - for_each_possible_cpu(cpu) { - cwq = init_cpu_workqueue(wq, cpu); - if (err || !cpu_online(cpu)) - continue; - err = create_workqueue_thread(cwq, cpu); - start_workqueue_thread(cwq, cpu); - } - cpu_maps_update_done(); + cpu_maps_update_begin(); + /* + * We must initialize cwqs for each possible cpu even if we + * are going to call destroy_workqueue() finally. Otherwise + * cpu_up() can hit the uninitialized cwq once we drop the + * lock. + */ + for_each_possible_cpu(cpu) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + struct global_cwq *gcwq = get_gcwq(cpu); + + BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); + cwq->gcwq = gcwq; + cwq->wq = wq; + cwq->flush_color = -1; + cwq->max_active = max_active; + INIT_LIST_HEAD(&cwq->worklist); + INIT_LIST_HEAD(&cwq->delayed_works); + + if (failed) + continue; + cwq->worker = create_worker(cwq, cpu_online(cpu)); + if (cwq->worker) + start_worker(cwq->worker); + else + failed = true; } - if (err) { + /* + * workqueue_lock protects global freeze state and workqueues + * list. Grab it, set max_active accordingly and add the new + * workqueue to workqueues list. + */ + spin_lock(&workqueue_lock); + + if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) + for_each_possible_cpu(cpu) + get_cwq(cpu, wq)->max_active = 0; + + list_add(&wq->list, &workqueues); + + spin_unlock(&workqueue_lock); + + cpu_maps_update_done(); + + if (failed) { destroy_workqueue(wq); wq = NULL; } return wq; +err: + if (wq) { + free_cwqs(wq->cpu_wq); + kfree(wq); + } + return NULL; } EXPORT_SYMBOL_GPL(__create_workqueue_key); -static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq) -{ - /* - * Our caller is either destroy_workqueue() or CPU_POST_DEAD, - * cpu_add_remove_lock protects cwq->thread. - */ - if (cwq->thread == NULL) - return; - - lock_map_acquire(&cwq->wq->lockdep_map); - lock_map_release(&cwq->wq->lockdep_map); - - flush_cpu_workqueue(cwq); - /* - * If the caller is CPU_POST_DEAD and cwq->worklist was not empty, - * a concurrent flush_workqueue() can insert a barrier after us. - * However, in that case run_workqueue() won't return and check - * kthread_should_stop() until it flushes all work_struct's. - * When ->worklist becomes empty it is safe to exit because no - * more work_structs can be queued on this cwq: flush_workqueue - * checks list_empty(), and a "normal" queue_work() can't use - * a dead CPU. - */ - trace_workqueue_destruction(cwq->thread); - kthread_stop(cwq->thread); - cwq->thread = NULL; -} - /** * destroy_workqueue - safely terminate a workqueue * @wq: target workqueue @@ -1086,72 +2004,270 @@ static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq) */ void destroy_workqueue(struct workqueue_struct *wq) { - const struct cpumask *cpu_map = wq_cpu_map(wq); - int cpu; + unsigned int cpu; + + flush_workqueue(wq); + /* + * wq list is used to freeze wq, remove from list after + * flushing is complete in case freeze races us. + */ cpu_maps_update_begin(); spin_lock(&workqueue_lock); list_del(&wq->list); spin_unlock(&workqueue_lock); + cpu_maps_update_done(); + + for_each_possible_cpu(cpu) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + int i; + + if (cwq->worker) { + spin_lock_irq(&cwq->gcwq->lock); + destroy_worker(cwq->worker); + cwq->worker = NULL; + spin_unlock_irq(&cwq->gcwq->lock); + } - for_each_cpu(cpu, cpu_map) - cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu)); - cpu_maps_update_done(); + for (i = 0; i < WORK_NR_COLORS; i++) + BUG_ON(cwq->nr_in_flight[i]); + BUG_ON(cwq->nr_active); + BUG_ON(!list_empty(&cwq->delayed_works)); + } - free_percpu(wq->cpu_wq); + free_cwqs(wq->cpu_wq); kfree(wq); } EXPORT_SYMBOL_GPL(destroy_workqueue); +/* + * CPU hotplug. + * + * CPU hotplug is implemented by allowing cwqs to be detached from + * CPU, running with unbound workers and allowing them to be + * reattached later if the cpu comes back online. A separate thread + * is created to govern cwqs in such state and is called the trustee. + * + * Trustee states and their descriptions. + * + * START Command state used on startup. On CPU_DOWN_PREPARE, a + * new trustee is started with this state. + * + * IN_CHARGE Once started, trustee will enter this state after + * making all existing workers rogue. DOWN_PREPARE waits + * for trustee to enter this state. After reaching + * IN_CHARGE, trustee tries to execute the pending + * worklist until it's empty and the state is set to + * BUTCHER, or the state is set to RELEASE. + * + * BUTCHER Command state which is set by the cpu callback after + * the cpu has went down. Once this state is set trustee + * knows that there will be no new works on the worklist + * and once the worklist is empty it can proceed to + * killing idle workers. + * + * RELEASE Command state which is set by the cpu callback if the + * cpu down has been canceled or it has come online + * again. After recognizing this state, trustee stops + * trying to drain or butcher and transits to DONE. + * + * DONE Trustee will enter this state after BUTCHER or RELEASE + * is complete. + * + * trustee CPU draining + * took over down complete + * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE + * | | ^ + * | CPU is back online v return workers | + * ----------------> RELEASE -------------- + */ + +/** + * trustee_wait_event_timeout - timed event wait for trustee + * @cond: condition to wait for + * @timeout: timeout in jiffies + * + * wait_event_timeout() for trustee to use. Handles locking and + * checks for RELEASE request. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock) which may be released and regrabbed + * multiple times. To be used by trustee. + * + * RETURNS: + * Positive indicating left time if @cond is satisfied, 0 if timed + * out, -1 if canceled. + */ +#define trustee_wait_event_timeout(cond, timeout) ({ \ + long __ret = (timeout); \ + while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ + __ret) { \ + spin_unlock_irq(&gcwq->lock); \ + __wait_event_timeout(gcwq->trustee_wait, (cond) || \ + (gcwq->trustee_state == TRUSTEE_RELEASE), \ + __ret); \ + spin_lock_irq(&gcwq->lock); \ + } \ + gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ +}) + +/** + * trustee_wait_event - event wait for trustee + * @cond: condition to wait for + * + * wait_event() for trustee to use. Automatically handles locking and + * checks for CANCEL request. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock) which may be released and regrabbed + * multiple times. To be used by trustee. + * + * RETURNS: + * 0 if @cond is satisfied, -1 if canceled. + */ +#define trustee_wait_event(cond) ({ \ + long __ret1; \ + __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ + __ret1 < 0 ? -1 : 0; \ +}) + +static int __cpuinit trustee_thread(void *__gcwq) +{ + struct global_cwq *gcwq = __gcwq; + struct worker *worker; + struct hlist_node *pos; + int i; + + BUG_ON(gcwq->cpu != smp_processor_id()); + + spin_lock_irq(&gcwq->lock); + /* + * Make all workers rogue. Trustee must be bound to the + * target cpu and can't be cancelled. + */ + BUG_ON(gcwq->cpu != smp_processor_id()); + + list_for_each_entry(worker, &gcwq->idle_list, entry) + worker->flags |= WORKER_ROGUE; + + for_each_busy_worker(worker, i, pos, gcwq) + worker->flags |= WORKER_ROGUE; + + /* + * We're now in charge. Notify and proceed to drain. We need + * to keep the gcwq running during the whole CPU down + * procedure as other cpu hotunplug callbacks may need to + * flush currently running tasks. + */ + gcwq->trustee_state = TRUSTEE_IN_CHARGE; + wake_up_all(&gcwq->trustee_wait); + + /* + * The original cpu is in the process of dying and may go away + * anytime now. When that happens, we and all workers would + * be migrated to other cpus. Try draining any left work. + * Note that if the gcwq is frozen, there may be frozen works + * in freezeable cwqs. Don't declare completion while frozen. + */ + while (gcwq->nr_workers != gcwq->nr_idle || + gcwq->flags & GCWQ_FREEZING || + gcwq->trustee_state == TRUSTEE_IN_CHARGE) { + /* give a breather */ + if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) + break; + } + + /* notify completion */ + gcwq->trustee = NULL; + gcwq->trustee_state = TRUSTEE_DONE; + wake_up_all(&gcwq->trustee_wait); + spin_unlock_irq(&gcwq->lock); + return 0; +} + +/** + * wait_trustee_state - wait for trustee to enter the specified state + * @gcwq: gcwq the trustee of interest belongs to + * @state: target state to wait for + * + * Wait for the trustee to reach @state. DONE is already matched. + * + * CONTEXT: + * spin_lock_irq(gcwq->lock) which may be released and regrabbed + * multiple times. To be used by cpu_callback. + */ +static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) +{ + if (!(gcwq->trustee_state == state || + gcwq->trustee_state == TRUSTEE_DONE)) { + spin_unlock_irq(&gcwq->lock); + __wait_event(gcwq->trustee_wait, + gcwq->trustee_state == state || + gcwq->trustee_state == TRUSTEE_DONE); + spin_lock_irq(&gcwq->lock); + } +} + static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) { unsigned int cpu = (unsigned long)hcpu; - struct cpu_workqueue_struct *cwq; - struct workqueue_struct *wq; - int err = 0; + struct global_cwq *gcwq = get_gcwq(cpu); + struct task_struct *new_trustee = NULL; + struct worker *worker; + struct hlist_node *pos; + unsigned long flags; + int i; action &= ~CPU_TASKS_FROZEN; switch (action) { - case CPU_UP_PREPARE: - cpumask_set_cpu(cpu, cpu_populated_map); + case CPU_DOWN_PREPARE: + new_trustee = kthread_create(trustee_thread, gcwq, + "workqueue_trustee/%d\n", cpu); + if (IS_ERR(new_trustee)) + return notifier_from_errno(PTR_ERR(new_trustee)); + kthread_bind(new_trustee, cpu); } -undo: - list_for_each_entry(wq, &workqueues, list) { - cwq = per_cpu_ptr(wq->cpu_wq, cpu); - - switch (action) { - case CPU_UP_PREPARE: - err = create_workqueue_thread(cwq, cpu); - if (!err) - break; - printk(KERN_ERR "workqueue [%s] for %i failed\n", - wq->name, cpu); - action = CPU_UP_CANCELED; - err = -ENOMEM; - goto undo; - - case CPU_ONLINE: - start_workqueue_thread(cwq, cpu); - break; - case CPU_UP_CANCELED: - start_workqueue_thread(cwq, -1); - case CPU_POST_DEAD: - cleanup_workqueue_thread(cwq); - break; - } - } + /* some are called w/ irq disabled, don't disturb irq status */ + spin_lock_irqsave(&gcwq->lock, flags); switch (action) { - case CPU_UP_CANCELED: + case CPU_DOWN_PREPARE: + /* initialize trustee and tell it to acquire the gcwq */ + BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); + gcwq->trustee = new_trustee; + gcwq->trustee_state = TRUSTEE_START; + wake_up_process(gcwq->trustee); + wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); + break; + case CPU_POST_DEAD: - cpumask_clear_cpu(cpu, cpu_populated_map); + gcwq->trustee_state = TRUSTEE_BUTCHER; + break; + + case CPU_DOWN_FAILED: + case CPU_ONLINE: + if (gcwq->trustee_state != TRUSTEE_DONE) { + gcwq->trustee_state = TRUSTEE_RELEASE; + wake_up_process(gcwq->trustee); + wait_trustee_state(gcwq, TRUSTEE_DONE); + } + + /* clear ROGUE from all workers */ + list_for_each_entry(worker, &gcwq->idle_list, entry) + worker->flags &= ~WORKER_ROGUE; + + for_each_busy_worker(worker, i, pos, gcwq) + worker->flags &= ~WORKER_ROGUE; + break; } - return notifier_from_errno(err); + spin_unlock_irqrestore(&gcwq->lock, flags); + + return notifier_from_errno(0); } #ifdef CONFIG_SMP @@ -1201,14 +2317,184 @@ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) EXPORT_SYMBOL_GPL(work_on_cpu); #endif /* CONFIG_SMP */ +#ifdef CONFIG_FREEZER + +/** + * freeze_workqueues_begin - begin freezing workqueues + * + * Start freezing workqueues. After this function returns, all + * freezeable workqueues will queue new works to their frozen_works + * list instead of the cwq ones. + * + * CONTEXT: + * Grabs and releases workqueue_lock and gcwq->lock's. + */ +void freeze_workqueues_begin(void) +{ + struct workqueue_struct *wq; + unsigned int cpu; + + spin_lock(&workqueue_lock); + + BUG_ON(workqueue_freezing); + workqueue_freezing = true; + + for_each_possible_cpu(cpu) { + struct global_cwq *gcwq = get_gcwq(cpu); + + spin_lock_irq(&gcwq->lock); + + BUG_ON(gcwq->flags & GCWQ_FREEZING); + gcwq->flags |= GCWQ_FREEZING; + + list_for_each_entry(wq, &workqueues, list) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + + if (wq->flags & WQ_FREEZEABLE) + cwq->max_active = 0; + } + + spin_unlock_irq(&gcwq->lock); + } + + spin_unlock(&workqueue_lock); +} + +/** + * freeze_workqueues_busy - are freezeable workqueues still busy? + * + * Check whether freezing is complete. This function must be called + * between freeze_workqueues_begin() and thaw_workqueues(). + * + * CONTEXT: + * Grabs and releases workqueue_lock. + * + * RETURNS: + * %true if some freezeable workqueues are still busy. %false if + * freezing is complete. + */ +bool freeze_workqueues_busy(void) +{ + struct workqueue_struct *wq; + unsigned int cpu; + bool busy = false; + + spin_lock(&workqueue_lock); + + BUG_ON(!workqueue_freezing); + + for_each_possible_cpu(cpu) { + /* + * nr_active is monotonically decreasing. It's safe + * to peek without lock. + */ + list_for_each_entry(wq, &workqueues, list) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + + if (!(wq->flags & WQ_FREEZEABLE)) + continue; + + BUG_ON(cwq->nr_active < 0); + if (cwq->nr_active) { + busy = true; + goto out_unlock; + } + } + } +out_unlock: + spin_unlock(&workqueue_lock); + return busy; +} + +/** + * thaw_workqueues - thaw workqueues + * + * Thaw workqueues. Normal queueing is restored and all collected + * frozen works are transferred to their respective cwq worklists. + * + * CONTEXT: + * Grabs and releases workqueue_lock and gcwq->lock's. + */ +void thaw_workqueues(void) +{ + struct workqueue_struct *wq; + unsigned int cpu; + + spin_lock(&workqueue_lock); + + if (!workqueue_freezing) + goto out_unlock; + + for_each_possible_cpu(cpu) { + struct global_cwq *gcwq = get_gcwq(cpu); + + spin_lock_irq(&gcwq->lock); + + BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); + gcwq->flags &= ~GCWQ_FREEZING; + + list_for_each_entry(wq, &workqueues, list) { + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + + if (!(wq->flags & WQ_FREEZEABLE)) + continue; + + /* restore max_active and repopulate worklist */ + cwq->max_active = wq->saved_max_active; + + while (!list_empty(&cwq->delayed_works) && + cwq->nr_active < cwq->max_active) + cwq_activate_first_delayed(cwq); + + /* perform delayed unbind from single cpu if empty */ + if (wq->single_cpu == gcwq->cpu && + !cwq->nr_active && list_empty(&cwq->delayed_works)) + cwq_unbind_single_cpu(cwq); + + wake_up_process(cwq->worker->task); + } + + spin_unlock_irq(&gcwq->lock); + } + + workqueue_freezing = false; +out_unlock: + spin_unlock(&workqueue_lock); +} +#endif /* CONFIG_FREEZER */ + void __init init_workqueues(void) { - alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL); + unsigned int cpu; + int i; + + /* + * The pointer part of work->data is either pointing to the + * cwq or contains the cpu number the work ran last on. Make + * sure cpu number won't overflow into kernel pointer area so + * that they can be distinguished. + */ + BUILD_BUG_ON(NR_CPUS << WORK_STRUCT_FLAG_BITS >= PAGE_OFFSET); + + hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); + + /* initialize gcwqs */ + for_each_possible_cpu(cpu) { + struct global_cwq *gcwq = get_gcwq(cpu); + + spin_lock_init(&gcwq->lock); + gcwq->cpu = cpu; + + INIT_LIST_HEAD(&gcwq->idle_list); + for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) + INIT_HLIST_HEAD(&gcwq->busy_hash[i]); + + ida_init(&gcwq->worker_ida); + + gcwq->trustee_state = TRUSTEE_DONE; + init_waitqueue_head(&gcwq->trustee_wait); + } - cpumask_copy(cpu_populated_map, cpu_online_mask); - singlethread_cpu = cpumask_first(cpu_possible_mask); - cpu_singlethread_map = cpumask_of(singlethread_cpu); - hotcpu_notifier(workqueue_cpu_callback, 0); keventd_wq = create_workqueue("events"); BUG_ON(!keventd_wq); }